Geochemical and isotope geochemical investigations on amphibolite-facies metabasites from the Spessart Crystalline basement, Mid-German Crystalline Zone

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The aim of this project is to unravel the petrogenesis of metabasic rocks from the Spessart crystalline basement, Mid German Crystalline Zone (MGCZ), as detailed as possible. At present, the source of the pre-metamorphic protoliths and the crustal evolution and geodynamic environments are only poorly constrained because of a lack of comprehensive lithogeochemical and isotope data sets. To fill this gap we plan to provide new lithogeochemical (major, minor, trace, including rare earth elements, REE), and Nd, Pb and Sr whole rock isotope data for mafic rocks from the Spessart basement. Using these geochemical and isotope data we aim to reconstruct the source areas and tectonic settings in which the rocks originally formed and/or were emplaced and distinguish these if possible, from the tectonic setting(s) in which the geochemical signature of the rocks was subsequently modified during their later tectonothermal history. The expected results should help to better constrain the geodynamic evolution of the Spessart crystalline basement and, by implication, of the MGCZ, i.e. to distinguish between potentially different crustal components and crustal age domains. More specifically, the new data are expected to help in assigning the source and tectonic evolution of these mafic rocks to Variscan and/or possibly other crust-forming events.